Revert Task.Yield() from AsyncWriteJournal and SnapshotStore (cherry-pick to dev)#8189
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Aaronontheweb merged 2 commits intoApr 26, 2026
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…napshotStore (akkadotnet#8163) This reverts the Task.Yield() additions from PR akkadotnet#8163 in AsyncWriteJournal.ExecuteBatch and SnapshotStore.ReceiveSnapshotStore, while preserving the health check test improvements from that same PR. PR akkadotnet#8163 added `await Task.Yield()` before calling `WriteMessagesAsync` and `SaveAsync` inside their respective circuit breaker lambdas. The intent was to move expensive byte serialization off the actor's message-processing thread, which showed ~45% throughput improvement in benchmarks. However, this silently broke the implicit contract that persistence plugins relied on: that the synchronous preamble of `WriteMessagesAsync`/`SaveAsync` executes in actor context. Moving execution to the thread pool caused: 1. Plugins that access `Self` inside `WriteMessagesAsync` (e.g. Akka.Persistence.Sql, Akka.Persistence.EventStore) throw `NotSupportedException` because there is no active ActorContext on a thread pool thread. 2. Plugins that use non-thread-safe collections like `Dictionary<string, Task>` for write tracking (e.g. Akka.Persistence.Sql, Akka.Persistence.EventStore) are now subject to concurrent access from both the actor thread and thread pool threads, causing `InvalidOperationException` or silent data corruption. 3. Plugins that send messages to subscribers after writes complete (e.g. Akka.Persistence.Redis) access shared actor state off the actor thread. The change was too blunt an instrument — it applied uniformly to all plugins via the base class, removing their ability to do any actor-thread setup before async work begins. Ironically, the plugins that benefit most from off-thread serialization (MongoDB, Azure Table Storage) don't access actor context at all, while the plugins that break (SQL, EventStore, Redis) already perform serialization off-thread in their async pipelines. A future version may reintroduce this optimization with a more surgical approach (e.g. opt-in property or Template Method pattern) that preserves the plugin threading contract.
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Summary
Cherry-pick of the v1.5.67 hotfix to
dev.Task.Yield()additions from PR Ensure WriteMessagesAsync/SaveAsync is called asynchronously in Async… #8163 inAsyncWriteJournal.ExecuteBatchandSnapshotStore.ReceiveSnapshotStoreSee #8188 and the v1.5.67 release notes for full context on why this was reverted.
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